In recent years, as portable electronic devices (e.g., mobile phones and digital cameras) become ubiquitous, much effort has been put into reducing dimensions of portable electronic devices. Moreover, as dimensions of charged coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) based optical sensors are reduced, dimensions of imaging lenses for use with the optical sensors must be correspondingly reduced without significantly compromising optical performance. However, the most important characteristics of imaging lenses are imaging quality and size.
Each of Japanese Patent No. 5397538 and Taiwanese Patent Application Publication No. 201305651 discloses a conventional imaging lens that includes five lens elements, and a system length (a distance between an object-side surface of a first lens element and an image plane at an optical axis) that is relatively larger, which cannot be effectively reduced to a certain length. These conventional configurations render the same unsuitable to be incorporated into a mobile phone or a digital camera with a thin design.
Therefore, greater technical difficulties are encountered for a miniaturized imaging lens than for traditional imaging lenses. Producing an imaging lens that meets requirements of consumer electronic products while having satisfactory optical performance is always a goal in the industry.